The present invention relates to wireless communication systems. More particularly, the present invention relates to a method and apparatus for improved signal reception with less multipath interference in wireless communication systems.
Many wireless communication systems utilize linearly polarized signal transmitters and linearly polarized signal receivers, which experience multipath signal interference. As illustrated in FIG. 1, a linearly polarized signal transmitting antenna 1 sends a linearly polarized signal that is frequently reflected off of one (or more) intervening object(s) 3 (for example, a building) between transmitting antenna 1 and the receiver station, which has a single linearly polarized signal receiving antenna 5. The reflected signal(s) and the initially transmitted linearly polarized signal often travel along multiple paths (indicated by 7 and 9, respectively) from transmitting antenna 1 to receiving antenna 5. Linearly polarized signals are more susceptible to having nulls in time and space domains in signal strength, and nulls in the signal can cause difficulty in implementing a high reliability wireless communication system. For example, when the receiving antenna 5 receives a signal in direct path 9 from transmitting antenna 1, the communication system operates without problems. However, if an additional signal is reflected off intervening object 3, the sum of the reflected and direct signals may be zero, with the result that receiving antenna 5 does not seem to receive any signal. Accordingly, multipath signal interference in systems using linearly polarized signals causes significant difficulty in the design and use of such wireless communication systems.
It is desirable to provide a method and system to improve the signal quality for wireless communication systems so that multipath signal interference is not such a significant problem in the design and use of wireless communication systems.